Python env

Node

• node_modules/
• package.json

Python

• venv/
• requirements.txt

Create Venv

python3 -m venv venv

Activate Venv

Windows (PowerShell or CMD):

.\venv\Scripts\activate

Mac / Linux:

source venv/bin/activate

Note for Windows PowerShell Users: If you get an error stating that running scripts is disabled (UnauthorizedAccess / Execution Policy error), run this command once to allow scripts for your user account:

Set-ExecutionPolicy RemoteSigned -Scope CurrentUser

Then try the activate command again.

Common Commands

Task	Command
Create env	python -m venv venv
Activate env	.\venv\Scripts\activate
Install package	pip install fastapi
Save deps	pip freeze > requirements.txt
Install deps	pip install -r requirements.txt
Run FastAPI	uvicorn app.main:app --reload

Database Architecture

Big Picture Architecture

flowchart TD
    A[Angular UI] -->|HTTP Request| B(FastAPI Backend)
    B -->|Database Query| C[(PostgreSQL Database)]

Loading

What Happens Internally?

flowchart TD
    A[FastAPI starts] --> B[SQLAlchemy connects]
    B --> C[Tables created]
    C --> D((Server listens for requests))

Loading

Complete Request Flow

flowchart TD
    A([Browser Request]) --> B[FastAPI Route]
    B --> C[Depends get_db]
    C --> D[Session Created]
    D --> E[ORM Query]
    E --> F[psycopg2 sends SQL]
    F --> G[(PostgreSQL responds)]
    G --> H([JSON returned])

Loading